Aside from the straw feminists certain FJ users seem to love, I can't imagine women opposing this on "patriarchy" grounds. For one thing, we'd get to have sexy man-bots as well.
The difficulty would be that people would want to find a way to program the robots to love. Even if such a thing were possible, we could never do it without them inevitably falling in love with other sex bots.
And we'd be back where we started, only with a bunch of sexy, unattainable robots running around.

That's perfectly true, there would be more female models, but the manufacturer couldn't ignore women and gay men without losing a good demographic. Even if there's only one male model to five female ones, that's just evidence of market pressures, not sexism.
As to the custom-pc-v-wii argument, that's true, but think about the range in computer usage, from hardcore gamers to people who just want internet access and word processing. Same with sex bots: you'd have people who understood and modded their machines extensively, while others would be perfectly happy with off-the-shelf features.

If it seems like I've put a lot of thought into this, it's because I'm writing a short story about a man and his robot "wife."